Dietary Protein Requirements
(How much protein do you need to consume each day?)
Learning Goals
? to calculate minimum dietary protein requirements based on body weight, age, and activity level
? to calculate Recommended Dietary Allowance (RDA) of protein based on Acceptable Macronutrient
Distribution Ranges (AMDR)
? to compare and contrast the above two approaches for determining daily protein needs
Model 1. Calculating Your Minimum Daily Protein Needs
Your minimum daily protein needs are determined based on your body weight, age, and approximate
activity level. The units are grams of protein needed per kilogram of body weight. Therefore, first convert
your weight into kilograms by using the equality 1 kg = 2.2 lb.
Example: For Morgan Spurlock, who weighed 185 kg before his month-long McDiet, which he
documented in Super Size Me, this would be …
84.1kg 2.2lb
1kg 185lb x ?
Next, multiply your weight in kilograms by the appropriate factor1,2 below:
If you are … you need this much protein:
14-18 years old 0.85 g/kg
= 19 years old (most adults) 0.8 g/kg
a nonvegetarian endurance athlete 1.2 to 1.4 g/kg
a nonvegetarian strength athlete 1.6 to 1.7 g/kg
a vegetarian endurance athlete 1.3 to 1.5 g/kg
a vegetarian strength athlete 1.7 to 1.8 g/kg
Table 1. Minimum daily protein requirements.
Example: As a New Yorker, Spurlock does a fair amount of walking, but he would not be
classified as an endurance (or a strength) athlete. Therefore, we will multiply his
weight in kilograms by 0.8 grams of protein per kilogram of body weight.
67.3g of proteindaily kgbody weight
0.8 gprotein 84.1kg x ?
For someone who exercises regularly (perhaps by working out at the gym three times a week and playing
pick-up basketball once a week), daily protein needs may be greater than 0.8 g/kg. In such a case, you
could calculate a range of daily protein needs—between 0.8 and 1.0 g/kg a day.
1 Blake. Nutrition & You: Core Concepts for Good Health; Pearson Benjamin Cummings: San Francisco, 2011, p 14|5. 2 Thompson, Manore, & Vaughn. The Science of Nutrition, 2nd ed.; Pearson Benjamin Cummings, 2011, p 228.
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2 A. L. Smith 2017
Critical Thinking Question
1. (A) Calculate your minimum daily protein needs using the information on the previous page. If you are
unsure which multiplication factor to use, calculate a range of values.
Model 2. Recommended Dietary Allowances for the Macronutrients
Another way to calculate protein needs is to use the Acceptable Macronutrient Distribution Ranges
(AMDR), as shown in the table below.
macronutrient percent of total daily caloric intake
carbohydrate 45-65%
fat 20-35%
protein 10-35%
Table 2. Acceptable Macronutrient Distribution Ranges.
Critical Thinking Questions
2. (E) Let’s assume that Morgan Spurlock wishes to have 55% of his daily kilocalories come from
carbohydrate, 25% from fat, and 20% from protein. Do these percentages fall within the Acceptable
Macronutrient Distribution Ranges listed in the table above?
3. (I) Let’s also assume that Morgan Spurlock needs approximately 3,000 kilocalories a day. If he wishes
to have 55% of his daily kilocalories come from carbohydrate, how many kilocalories would this be?
4. (A) How many kilocalories would he consume from fat if 25% of his 3000 daily kilocalories come from
fat?
5. (A) How many kilocalories would he consume from protein if 20% of his 3000 daily kilocalories come
from protein? Confirm your answers for questions 2-5 with your group.
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Model 3. Calculating Protein RDA from AMDR
Using the information in Model 2, we can calculate Morgan Spurlock’s recommended dietary allowance
(RDA) for protein in grams. Keep in mind that each gram of protein consumed provides the body with
4 kilocalories of energy. This information, along with the corresponding data for carbohydrates and fats,
is given in the table below
macronutrient kilocalories per gram
carbohydrate 4 kcal/g
fat 9 kcal/g
protein 4 kcal/g
Table 3. Kilocalorie values of the macronutrients.
Critical Thinking Questions
6. (E) According to the table above, which macronutrient—carbohydrate, fat, or protein—provides the
greatest number of kilocalories per gram?
7. (E) Which two macronutrients provide the same amount of energy per gram?
8. (I) Divide the number of kilocalories of carbohydrate you calculated in question 3 by the number of
kilocalories per gram that carbohydrate provides. This is the number of grams of carbohydrate that
Morgan Spurlock should consume each day.
9. (A) Repeat the process you did in question 8 to determine the number of grams of fat that Morgan
Spurlock should consume each day. Use the number of kilocalories of fat you calculated in question 4 in
your calculation.
10. (A) Repeat this process for protein, using your answer from question 5 in your calculation.
11. (A) Compare Morgan Spurlock’s minimum daily protein needs (calculated in the second example box
on the first page of this activity) to the protein RDA you calculated in question 10. Which value is
greater? By how much? Confirm your answers for questions 6-11 with your group.
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Exercises
The exercises below will help to summarize and reinforce the information in this activity. You will find
much of the information within the activity itself, and you may need to use your textbook to find other
information. You should complete these exercises after class either on your own or in a group.
1. By what factor should most adults multiply their weight (in kilograms) in order to calculate their
minimum daily protein requirement? How does this factor change with activity level and type of
activity?
2. Using the AMDR given above and your own EER (which you can calculate or find using diet analysis
software), calculate the upper and lower limits of your carbohydrate, fat, and protein RDA’s. How does
your protein RDA range compare to the daily protein needs you calculated
